Hi Roy, and welcome!
It doesn’t? Thank goodness you’re here to tell us, I guess the tens of thousands of people programming in Python can just stop, now that we know it doesn’t work! 
I can’t run your code right now, but at a glance my guess is that your unwanted grey square might have something to do with your code here:
new_segment.shape(“square”)
new_segment.color(“grey”)
where, I think, you create and draw a grey square. What happens if you remove those two lines?
In future, please format your code correctly, as Python code, using the </> button. You can see a preview of the code to the side of the text entry widget on the Discuss website, so you can check to see how it looks before posting.
(You might need to close the " Your topic is similar to…" window which pops up and obscures the preview.)
It might also help us all if you can simplify your example code to the minimal reproducible example that demonstrates the problem. That makes it easier for us to help you.